The present invention relates to a signal-processing apparatus which is mounted on typically recording apparatus, used for inputting data, carrying out a predetermined encoding process on the input data and outputting the encoded data as data to be recorded, as well as relates to a signal-processing method adopted by the signal-processing apparatus.
The so-called MD (Mini Disk) has been becoming very popular in recent years as media that can be used for recording and playing back audio data. The MD is a kind of magneto-optical disk which has a disk shape and can be used for recording and playing back audio data in accordance with a magneto-optical system.
As is generally known, in recording and playback apparatus for recording data onto and playing back data from an MD, compressed audio data is transferred into a buffer memory at a predetermined transfer speed during a recording operation to be stored in the buffer memory. An operation to write data from the buffer memory into the MD is carried out when the amount of data stored in the buffer memory exceeds a predetermined value. The data is read out from the buffer memory at a transfer speed higher than the transfer speed used during the operation to write data into the buffer memory. Before being written into the MD, the data is subjected to a predetermined modulation process appropriate for the disk recording. The modulation process includes EFM modulation and addition of error correction codes. The operation described above is carried out repeatedly. That is to say, in a recording operation, data is written into the disk intermittently.
In addition, in an MD format, a smallest recording unit of data is prescribed. The smallest recording unit is referred to as a cluster. That is to say, during an interval of the intermittent recording described above, data of at least 1 cluster is written into the disk.
Typically, the structure of a cluster is an array of 36 smaller data units each called a sector. The head of a cluster typically comprises 3 such sectors serving as an area for linking. Referred to as a linking area, the area for linking is not used for storing actual data. A data area follows the linking area. A middle position of the linking area of a cluster is prescribed as a linking point serving as a linking position between the cluster and the preceding cluster. The operation to record data and the processing to play back a predetermined signal in cluster units are carried out with this linking point taken as a reference point.
The power of a laser beam radiated to the MD during a recording operation carried out intermittently as described above is set at a high level in a period of time to write data into the disk. The high-level power of the laser beam is referred to as a write power. During a pause period in which no data is written onto the disk, on the other hand, the power of the laser beam is set at a low level corresponding to a playback operation. The low-level power of the laser beam is referred to as a read power.
By setting a write power during a data-writing period, the signal surface of the disk can be heated to a Curie temperature. During a pause period, on the other hand, the read power is set, allowing address information recorded on an MD track as the so-called zigzag groove to be read out from the MD track so as not to damage the data which has been already recorded on the disk.
In a transition from a pause period to a data-writing period, the power of the laser beam is switched from the read power to the write power with a timing to start an operation to write data into the disk from a position indicated by the linking point described above.
It is thus necessary to issue a command as to a timing to start an operation to supply typically a sector including the linking point as a timing to start operations to read out data from the buffer memory and supply the data to be recorded to an encoding process circuit.
In addition, it is also necessary to issue a command for switching the power of the laser beam from the read power to the write power with a timing to output the linking point described above from the encoding process circuit after a delay time required for carrying out an encoding process in the encoding process circuit.
Such timing control is executed in the recording and playback apparatus by a system controller employing typically a microcomputer and other components. The system controller obtains information on an address in a disk by communication with typically the encoding process circuit. Then, while monitoring addresses, the system controller measures time from typically the number of EFM frames. From the measured time, the system controller obtains a timing to start an operation to supply data to be recorded to the encoding process circuit. With this timing, the system controller outputs a data-input-start control signal to start a transfer of data from the buffer memory to an EFM signal processing system. In addition, the system controller also obtains information on a timing to switch the power of the laser beam from the read power to the write power. With this timing, the system controller outputs a laser-power-switching control signal to a driving circuit of a laser diode.
It should be noted that an EFM frame cited above is one of units for handling data to be recorded as EFM-modulated data. For example, 1 sector consists of 98 EFM frames each corresponding to a time duration of 13.3 ms.
In accordance with the MD format, the precision of the data-input-start-control signal shall be in the range of 36 frames, that is, from xe2x88x9210 frames to +26 frames. Expressed in terms of time, the range corresponds to about 5 ms at a 1-time CLV (Constant Linear Velocity).
On the other hand, stricter precision of +/xe2x88x9210 EFM frames is prescribed for the laser-power-switching control signal in order to keep up with a timing of a single point on data, namely, the linking point. Expressed in terms of time, the range of this precision corresponds to about 1.3 ms at a 1-time CLV.
If the margin of each of the precision ranges is exceeded, for example, linking of data to be recorded becomes unstable, deteriorating the quality and it is quite within the bounds of possibility that a playback error is generated during a playback operation. The system controller operates to output each of the control signals described above, within the margins of the ranges described above.
By the way, as is already known in recent years, it is possible to record data onto an MD at a multiple-time speed, that is, a speed higher than the 1-time CLV cited above, and there is a trend to promote an effort to further increase the multiple-time speed.
At a higher recording speed, the time margin of the timing control executed at the start of a recording operation becomes stricter. Thus, the system controller is required to operate with an even higher degree of precision.
Since the signal-processing timing of a modulation processing circuit is controlled by an external controller, however, there is a limit on the improvement of the degree of precision with which the system controller executes the timing control at the start of a recording operation. If data is to be recorded at an extremely high speed, for example, it will be quite within the bounds of possibility that a sufficiently good quality of recorded data can no longer be guaranteed.
It is thus an object of the present invention addressing the problems described above to maintain a sufficiently good quality of recorded data by execution of an operation required at the start of a recording operation with a highly precise timing, even at a higher recording speed.
In order to achieve the object described above, the present invention provides a signal-processing apparatus for carrying out a recording operation to record data onto a recording medium in predetermined recorded-data units. The recorded-data unit is an array consisting of a predetermined number of division-data units each comprising a predetermined number of encoded-data units. The signal-processing apparatus also carries out signal processing for the recording operation in conformity with a format prescribing a linking area for linking consecutive recorded-data units to each other.
The signal-processing apparatus comprises an encoding means for inputting data, carrying out predetermined signal processing suitable for an operation to record the input data onto the recording medium and outputting data to be written into the recording medium and a timing generation means for generating a timing signal indicating a timing to start an operation to provide the encoding means with the division-data units including a linking point described in the linking area by counting the predetermined number of the encoded-data units with a timing to detect address information for a specific one of the division-data units from the recording medium.
In addition, the present invention also provides a signal-processing method for carrying out a recording operation to record data onto a recording medium in predetermined recorded-data units. The recorded-data unit is an array consisting of a predetermined number of division-data units each comprising a predetermined number of encoded-data units. In accordance with the signal-processing method, signal processing is also carried out for the recording operation in conformity with a format prescribing a linking area for linking consecutive recorded-data units to each other.
The signal-processing method comprises the steps of carrying out an encoding process to input data, perform predetermined signal processing suitable for an operation to record the input data onto the recording medium and output data to be written into the recording medium and carrying out a timing generation process to generate a timing signal indicating a timing to start processing carried out in the encoding process on the division-data units including a linking point described in the linking area by counting the predetermined number of encoded-data units with a timing to detect address information for a specific one of the division-data units from the recording medium.
Furthermore, the present invention also provides another signal-processing apparatus for carrying out a recording operation to record data onto a recording medium in predetermined recorded-data units. The recorded-data unit is an array consisting of a predetermined number of division-data units each comprising a predetermined number of encoded-data units. The other signal-processing apparatus also carries out signal processing for the recording operation in conformity with a format prescribing a linking area for linking consecutive recorded-data units to each other.
The other signal-processing apparatus comprises an encoding means for inputting data, carrying out predetermined signal processing suitable for an operation to record the input data onto the recording medium and outputting data to be written into the recording medium, a timing generation means for generating a timing signal indicating a timing to start an operation to provide the encoding means with division-data units including a linking point each described in the linking area by counting the predetermined number of encoded-data units with a timing to detect address information for a specific one of the division-data units from the recording medium and a linking-point detection means for detecting a timing to output a signal indicating the linking point from the encoding means by counting the predetermined number of encoded-data units with a timing to detect address information for a specific one of the division-data units from the recording medium.
Moreover, the present invention also provides another signal-processing method for carrying out a recording operation to record data onto a recording medium in predetermined recorded-data units. The recorded-data unit is an array consisting of a predetermined number of division-data units each comprising a predetermined number of encoded-data units. In accordance with the other signal-processing method, signal processing is also carried out for the recording operation in conformity with a format prescribing a linking area for linking consecutive recorded-data units to each other.
The other signal-processing method comprises the steps of carrying out an encoding process to input data, perform predetermined signal processing suitable for an operation to record the input data onto the recording medium and output data to be written into the recording medium, carrying out a timing generation process to generate a timing signal indicating a timing to start processing carried out in the encoding process on the division-data units including a linking point described in the linking area by counting the predetermined number of encoded-data units with a timing to detect address information for a specific one of the division-data units from the recording medium and carrying out a linking-point detection process to detect a timing of the encoding process to output a signal indicating the linking point by counting the predetermined number of encoded-data units with a timing to detect address information for a specific one of the division-data units from the recording medium.
As described above, the present invention provides signal-processing apparatuses and signal-processing methods adopted in the signal-processing apparatuses for recording data onto a recording medium in predetermined recorded-data units wherein the recorded-data unit is an array consisting of a predetermined number of division-data units each comprising a predetermined number of encoded-data units, and for carrying out signal processing for the recording operation in conformity with a format prescribing a linking area.
The number of encoded-data units is counted on the basis of specific address information detected from the recording medium in order to specify a timing to start signal processing or to detect a timing to indicate a linking point of output data according to the specified timing to start the signal processing.
In such a configuration, the detection of a timing to start signal processing and a timing to indicate a linking point do not rely on control executed by an external controller. Instead, a timing to start signal processing and a timing to indicate a linking point can be detected only by means inside the signal-processing apparatus.
The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols.